Manufacture of sheets or webs of fibrous textile materials



Sept. 19, 1950 J. H. M GREGOR ETAL 2,522,527 mum-"11cm 0F sm'rs OR was 0F FIBROUS mum MATERIALS Filed Feb. 17, 1949 JAMLS HUTCH/SON MACGREGOR FRANK HA PPE Y mwzurons BY THE/R A TTORNE Y5 MM)W Patented Sept. 19, 1950 UNITED STATES PATENT OFFICE MANUFACTURE OF SHEETS OR WEBS FIBRQUS ,TEXTILE MATERIALS James H. MacGregor, Booking, Braintree, and Frank Happey, Hartington Crescent, Coventry, England, assignors to Courtaulds Limited, London, England, a British company Application February 17, 1949, Serial No. 76,892 In Great Britain March 4,1948

9 Claims.

This invention relates to the manufacture of sheets or webs of fibrous-textile materials, such tially-adhesive fibres, that is fibres which can be rendered adhesive by suitable treatment such as by heating. pressing or treating with a solvent, and to treat the blend subsequently in order to render adhesive the potentially-adhesive fibres and to bind the fibres together. For example, in void British application No. 10,246/1938 as laid open to public inspection, sheets or other shaped bodies of fibrous materials and felt substitutes are made by carding natural or artificial fibres in admixture with threads of thermoplastic artificial material and subjecting the card fleece or web to pressure, if desired with the application of heat.

The object of the present invention is to improve the manufacture of sheets of fibrous textile materials by the use of particular potentiallyadhesive fibres.

In accordance with the present invention, a process for the manufacture of sheets of fibrous textile materials comprises forming a layer of fibres consisting wholly 'or partly of fibrous cyanoethylated cellulose which has been prepared by etherifying cellulose with acrylonitrile whilst maintaining its fibrous structure and. rendering the fibrous cyanoethylated cellulose adhesive so that the fibres in the layer are bonded together; the fibres are preferably rendered adhesive by treatment with suitable solvents, with the simultaneous or subsequent application of pressure. The fibres may also be rendered adhesive by heating.

It is a ready known from United States Patent No. 2,375,847 that cellulose fibres may be etherified by reaction with acrylonitrile under conditions in which the fibrous form of the cellulose is maintained. The etherification is preferably carried out by soaking cellulose fibres in an aqueous solution, for example of 0.5 to 5 per cent strength, of an alkaline catalyst such as caustic alkali, an alkali metal cyanide or a quaternary ammonium hydroxide, centrifuging the fibres to remove excess catalyst solution and then reacting the fibres heterogeneously with acrylonitrile in the presence of a non-polar inert diluent such as benzene or toluene, so as to introduce cyanoethyl (-O-CHz-CHr-CN) groups into the (Cl. l54--101) 2 cellulose. The fibrous products obtained are heterogeneous and we have found, mainly from X-ray analyses that the products comprise an accessible cyanoethyl cellulose phase anda nonetherified cellulose phase. A typical cross-section considerably enlarged, of a fibrous cyanoethylated cellulose is illustrated in the accompanying diagrammatic drawings. The fibre'comprises an accessible cyanoethyl phase A. which surrounds and merges into a crystalline.non-etherified cellulose B; in the drawing a: line separation of the cyanoethyl cellulose A and the non-etherlfied cellulose B is shown for clarity, but actually the two materials are separated by zones of graded intercrystallinecellulose. The present invention takes advantage of the presence of the cyanoethyl cellulose phase in the fibre by causing it to act as the adhesive material for bonding the fibres together.

The heterogeneous cyanoethylation process produces two different types of fibrous cyanoethyl cellulose and both types are suitable for use in the present invention. The first type of fibrous cyanoethyl cellulose is that in which the nitrogen content, based on the weight of the dry ash-free cyanoethyl cellulose, does not exceed about 9 per cent, for example, from about 2 to about 9 per cent and with this type of ether the cyanoethyl cellulose forming the potentially-adhesive phase of the fibres is not rendered adhesive by water or organic solvents for example acetone or metacresol but isswollen readily by dilute aqueous solutions of caustic alkalies and quaternary ammonium hydroxides and these solutions may be used to render the fibre adhesive when this type of fibre is used in the process according to the present invention; 3 per cent aqueous solutions of the agents are suitable. This type of fibrous cyanoethyl cellulose is also swollen by moderately strong aqueous solutions of such metal salts as sodium thiocyanate, ammonium thiocyanate, calcium thiocyanate and zinc chloride; for example, a 25 per cent aqueous am-' monium thiocyanate solution. readily swells the fibres.

The second type of fibrous cyanoethyl cellulose is that in which the nitrogen content, also based on the weight of the dry ash-free cyanoethyl cellulose is within the range of about 9 to about 11 per cent. The cyanoethyl cellulose forming the potentially-adhesive phase in this type is insoluble in and is not swollen by water or by aqueous caustic alkali solutions but is swollen by organic solvents such as acetone, acrylonitrile, betaethoxy-propionitrile, dimethyl formamide,

methyl formate and m cresol and these agents may be used to render the fibre adhesive when this type of fibre is used in the process according to the invention. The solvent may be used with -or without the application of heat.

After treatment with the solvent or swelling agent, the layer of fibres is preferably partly dried for example to 20 per cent retained solvent, before being subjected to pressure and when using alkaline swelling agents, it is desirable to dry the treated layer of fibres partly, to press the layer if desired and then to remove the alkali, for ex-- ample by washing in acid solutions before the final drying.

The fibrous cyanoethylated cellulose fibres may be prepared from natural cellulose such as cotton and the bast fibres such as hemp, ramie, Jute and flax, or from regenerated cellulose such as viscose rayon fibres in either continuous or discontinuous lengths.

The layer of fibres may be built up from the fibrous cyanoethylated cellulose fibres alone or from mixtures of these fibres and other natural or synthetic fibres such as cotton, wool, casein fibres, viscose rayon and cellulose acetate rayon, the swelling medium being so chosen that the added fibres are substantially unafiected during the step of rendering the fibrous cyanoethylated cellulose fibres adhesive.

The layer of fibres may be prepared by carding the fibres to form a carded web or several carded webs may be overlaid and laminated together. Continuous filaments may also be formed into several laps of single filament thickness and the layers assembled on top of each other with the filaments in adjacent laps crossing at approximately 90. The layer may also be formed from a slurry of fibres in a-manner similar to the process used in the paper industry.

Before carding the fibres, they are preferably treated with a weak aqueous solution of a paraflin chain salt, for example cetyl trimethyl ammonium bromide, in order .to reduce the tendency of the filaments to stick together and also to improve the handle and carding properties of the fibres. The invention is illustrated by the following examples in which the parts and percentages are by weight.

Example 1 1 part of viscose rayon staple fibres was soaked for 30 minutes in a 1 per cent aqueous caustic soda solution at 17 centigrade and then centrifuged to remove excess liquid; the centrifuged fibres retained their own weight of solution. The fibres were transferred to a vessel fitted with a reflux condenser, and a mixture of 50 parts of acrylonitrile and 50 parts of benzene was added.

The vessel was then heated for 30 minutes at 50-60 centigrade on a water bath and the fibres were then removed and washed with alcohol and water until the washings were neutral to Universal Indicator. A dried sample of the fibres, on analysis by the Kjeldahl method, contained 8.5 per cent of nitrogen based on the dry ashfree ether. The cyanoethylated fibres were then soaked for 20 minutes in a 0.1 per cent aqueous solution of cetyl trimethyl ammonium bromide at 40 centigrade, rinsed in water and dried. The dried fibres were unaffected by acetone but were readily swollen by a 3-4 per cent aqueous caustic soda solution; the water imbibition of the fibres was 52 per cent.

The fibres were then carded to form a web of fibres which was sprayed with a 3 per cent aqueous caustic soda solution to render the fibres adcasein staple fibres.

Erample 2 1 part of viscose rayon staple fibres was soaked for 30 minutes in a 1 per cent aqueous caustic soda solution at 17 centigrade and then centrifuged to remove excess liquid; the centrifuged fibres retained their own weight of solution. The fibres were transferred to a vessel fitted with a reflux condenser, and a mixture of 50 parts of acrylonitrile'and 50 parts of benzene was added. The vessel was then heated for 1 hour on a water bath at centigrade. The fibres were removed from the vessel, washed with water and alcohol and dried at 70 centigrade. The fibres on analysis, contained 10.4 per cent of nitrogen, based on the dry ash-free sample. The cyanoethylated fibres were then soaked for 20 minutes in a 0.1 per cent aqueous solution of sodium dioctyl sulphosuccinate at 40 centigrade, rinsed with water and dried at 70 centigrade. The fibres obtained were unafiected by water and dilute alkaline solutions but were readily swollen by acetone; their water imbibition was 34 per cent.

The fibres were then carded to form a fibrous Web which was sprayed with acetone to render the fibres adhesive. The acetone was allowed to evaporate at 20 centigrade and a non-woven bonded fabric was obtained.

A more compact fabric was obtained by lightly pressing the web before or during evaporation of the acetone.

What we claim is:

1. A process for the manufacture of sheets of fibrous textile material which comprises forming a layer consisting at least in part of cyanoethyl cellulose ether fibers having a nitrogen content of from about 2 to about 11 per cent on the weight of the dry, ash-free fiber, said fibers having internal elements of unetherified cellulose and rendering the cyanoethylated cellulose adhesive whereby the fibers in the layer are bonded together.

2. A process for the manufacture of sheets of fibrous textile material which comprises etherifying cellulose fibers with acrylonitrile whilst maintaining their fibrous structure and stopping the reaction when the nitrogen content of the said fibers, based on the weight of the dry, ash-free fiber, is within the range of about 2.0 per cent to about 11.0 per cent, whereby the resulting fibers comprise a cyanoethyl cellulose phase surrounding non-etherified cellulose, drying the fibers, forming a layer of fibers at least 50 per cent of which consists of such partially cyanoethylated cellulose fibers and rendering the cyanoethyl cellulose phase of the fibers adhesive whereby the fibers in the layer are bonded together at their points of contact to form a sheet containing partially cyanoethylated cellulose fibers.

3. A process for the manufacture of sheets of fibrous textile material which comprises etherifying cellulose fibers with acrylonitrile whilst maintaining their fibrous structure and stopping the 5 reaction when the nitrogen content of the said fibers, based on the weight of the dry, ash-free fiber, is within the range of about 2.0 per cent to about 9 per cent whereby the resulting fibers comprise a cyanoethyl cellulose phase surrounding non-etherified cellulose, drying the fibers, forming a layer of fibers at least 50 per cent of which consists of such partially cyanoethylated cellulose fibers and rendering the cyanoethyl cellulose phase of the fibers adhesive by treatment with a dilute aqueous solution of a caustic alkali whereby the fibers in the layer are bonded together at their points of contact to form a sheet containing partially cyanoethylated cellulose fibers.

- 4. A process for the manufacture of sheets of fibrous textile material which comprises etherifying cellulose fibers with acrylonitrile whilst maintaining their fibrous structure and stopping the reaction when the nitrogen content of the said fibers, based on the weight of the dry, ash-free fiber, is within the range of about 2.0 per cent to about 9 per cent whereby the resulting fibers comprise a cyanoethyl cellulose phase surrounding non-etherified cellulose, drying the fibers, forming a layer of fibers at least 50 per cent of which consists of such partially cyanoethylated cellulose fibers and rendering the cyanoethyl cellulose phase of the fibers adhesive by treatment with a dilute aqueous solution of quaternary ammonium hydroxide whereby the fibers in the layer are bonded together at their points of contact to form a sheet containing partially cyanoethylated cellulose fibers.

5. A process for the manufacture of sheets of fibrous textile material which comprises etherifying cellulose fibers with acrylonitrile whilst maintaining their fibrous structure and stopping the reaction when the nitrogen content of the said fibers, based on the weight of the dry, ash-free fiber, is within the range of about 9 per cent to 11 per cent, whereby the resulting fibers comprise a cyanoethyl cellulose phase surrounding non-etherified cellulose, drying the fibers, forming a layer of fibers at least 50 per cent of which consists of such partially cyanoethylated cellulose fibers and rendering the cyanoethyl cellulose 7 phase of the fibers adhesive by treatment with acetone whereby the fibers in the layer are bonded together at their points of contact to form a sheet 1 cyanoethylated cellulose fibers having a nitrogen content, based on the weight of the dry, ashiree fiber, within the range of about 2 to about 11 per cent.

- 7. A process for the manufacture of sheets of fibrous textile material which comprises forming a layer consisting substantially oi cyanoethyl cellulose ether fibers having a nitrogen content of from aboutz to about 11 per cent on the weight of the dry, ash-free fibers, said fibers having internal elements of unetherified cellulose, and rendering the cyanoethylated cellulose adhesive whereby the fibers in the layer are bonded together.

8. A process for the manufacture of sheets of fibrous textile material which comprises etherifying cellulose fibers with acrylonitrile whilst maintaining their fibrous structure and stopping the reaction when the nitrogen content of the fibers based on the weight of the dry, ash-free fiber, is within the range of about 2 to about 11 per cent whereby the resulting fibers comprise a cyanoethyl cellulose phase surrounding non-etherified cellulose, drying the fibers, forming a layer of fibers, substantially all of which consists of such partially cyanoethylated cellulose fibers, and rendering the cyanoethyl cellulose phase of the fibers adhesive, whereby the fibers in the layer are bonded together at their points of contact to form a sheet consisting of partially cyanoethylated cellulose fibers.

9. A sheet of fibrous non-woven textile material, consisting of substantially all partially cyanoethylated cellulose fibers having a nitrogen content based on the weight of the dry, ash-free fiber within the range of about 2 to about 11 per cent, each of said fibers comprising a cyanoethyl cellulose phase surrounding non-etherified cellulose, said cyanoethyl cellulose phase bonding the fibers of the material together.

JAMES H. MACGREGOR. FRANK HAPPEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. A PROCESS FOR THE MANUFACTURE OF SHEETS OF FIBROUS TEXTILE MATERIAL WHICH COMPRISES FORMING A LAYER CONSISTING AT LEAST IN PART OF CYANOETHYL CELLULOSE ETHER FIBERS HAVING A NITROGEN CONTENT OF FROM ABOUT 2 TO ABOUT 11 PER CENT ON THE WEIGHT OF THE DRY, ASH-FREE FIBER, SAID FIBERS HAVING INTERNAL ELEMENTS OF UNETHERFIED CELLULOSE AND RENDERING THE CYANOETHYLATED CELLULOSE ADHESIVE WHEREBY THE FIBERS IN THE LAYER ARE BONDED TOGETHER. 